The present invention relates to fuel supply apparatus with a fuel metering valve for mixture-compressing, externally or remotely ignited combustion engines. Continuous fuel delivery takes place to the suction (intake) pipe which has an air funnel or diffuser that operates jointly with a coaxially located and axially movable throttle body. The latter is adjustable in opposition to a restoring force via the suction pipe underpressure acting in a working chamber which can be vented to the atmosphere.
Such an apparatus is known from U.S. Pat. No. 2,544,111. However, this apparatus has the disadvantage that the fuel flow determined by the fuel metering valve (actuated by the gas pedal) determines the amount of valve opening for venting the working chamber by mechanical coupling via a linkage. This results in a mixture with a fuel ratio which does not correspond to the rate of air flow; as a result, under all load conditions except idling, there results a fuel ratio which does not correspond to the motor (engine) load condition since there is no direct association between air quantity and fuel quantity, and the fuel quantity depends solely on the position of the gas pedal. In addition, during load change in the partial load range, the position of the throttle body cannot be defined by the changing suction pipe underpressure; this is because there is continuous venting of the working chamber via the valve, causing forces varying in size and direction to act continuously on the thorttle body. Therefore, this device does not permit continuous acceleration in the partial load range.
It is, therefore, an object of the present invention to provide fuel supply apparatus where the fuel is added depending on the rate of air flow and on the suction tube pressure difference, with the throttle body controlling the fuel metering valve so that a predetermined fuel-air ratio is assured and the throttle body performs a stroke in accordance with the gas pedal position.
It is another object of the present invention to provide fuel supply apparatus of the foregoing character which is substantially simple in design and construction, and may be economically fabricated.
A further object of the present invention is to provide a fuel supply arrangement, as described, which may be readily maintained in service, and which has a substantially long operating life.